1. Field of the Invention
The present invention relates to a vehicle-use head-up display system which reflects the light of a display-image of a luminous display unit capable of displaying an image including information about a vehicle toward a translucent reflecting means arranged in a visual field ahead of a driver""s seat by means of a reflecting means so that a driver can look at a virtual image in front of a windshield of a vehicle, wherein a display position of the virtual image can be adjusted in a state that a depression angle does not change even if an eye point of the driver changes within an eye range.
2. Description of the Related Art
As an example, there is a prior art system with a structure shown in FIG. 6. In this figure, a luminous display unit 111 having a fluorescent display tube, a liquid crystal or the like is arranged in a non-shown dashboard with its display surface directed toward the front of a vehicle. A reflecting mirror 113 to reflect the light of the display-image of this display unit 111 is arranged with a fixed angle relative to the display surface of the display unit 111. Here, though not illustrate, the light of the display-image of the display unit 111 can be projected on the reflecting mirror 113 through the Fresnel lens being an expansion optical system.
And, the reflecting mirror 113 reflects the light of the display-image of the display unit 111 toward an inner surface of a windshield (a front glass) 20 of the vehicle through an opening of a non-shown dashboard top face. On the inner surface, on the cabin side, of the windshield 20, a translucent reflection coating 21 to reflect the display-image reflected by the reflecting mirror 113 in a sight line direction of a driver is formed. By this, a driver can look at the display-image of the display unit reflected by the reflecting mirror 113 and the translucent reflection coating 21 as a virtual image ahead of the windshield.
Here, though not illustrate, the luminous display unit 111 and the reflecting mirror 113 are accommodated in a casing. Reference numerals 30 and 31 denote eye points and an eye range.
The eye range 30 defines a range or scope from which the display, i.e. the image, reflected by the translucent reflection coating 21 shall be looked at.
In order to assure a driver, i.e. the eye point, to be able to look at the display from the whole eye range, an adjusting mechanism to adjust the position of the display-image is provided on the system. When the eye points of a driver vertically move in the eye range for example, the adjusting mechanism linearly moves the reflecting mirror 113 as shown and turns the reflecting mirror 113 also as shown so that a depression angle can be unchanged.
With respect to the above prior art the adjusting mechanism, however, the turning adjustment of the reflecting mirror 113 is very difficult because a difference of angle, i.e. the difference between angles xcex1 and xcex2, is very small when the windshield stands nearly vertically like a truck.
In view of the foregoing, an object of the present invention is to provide a head-up display system wherein a positioning adjustment of the display-image can be precisely carried out when the eye points vertically move.
In order to achieve the above object, as a first aspect of the present invention, a vehicle-use head-up display system comprises: a luminous display unit to display an image including information about a vehicle; a reflecting means to reflect light of the display-image of the luminous display unit; a translucent reflecting means arranged on a windshield ahead of a driver""s seat, reflecting the light of the display-image from the reflecting means, and having a driver look at a virtual image on the windshield; a moving means to linearly move the reflecting means in a back-and-forth direction of the vehicle; and a display-image moving means to upwardly move the display-image of the luminous display unit in accordance with a backward movement of the reflecting means by the moving means and to downwardly move the display-image of the luminous display unit in accordance with a forward movement of the reflecting means by the moving means, wherein a display position is adjusted such that a depression angle does not change when an eye point in an eye range changes.
According to the above vehicle-use head-up display system, the display-image moving means upwardly moves the display-image of the luminous display unit with the backward movement of the reflecting means, and downwardly moves the display-image of the luminous display unit with the forward movement of the reflecting means, so that the depression angle is not changed by adjusting the display position. Therefore, when looking at the display at a different eye point in the eye range, the display-image only has to be vertically shifted and the reflecting means only has to be linearly-moved in a back-and-forth direction.
As a second aspect of the present invention, based on the first aspect, the display-image moving means is a display unit moving means to vertically move the luminous display unit.
According to the above vehicle-use head-up display system, the luminous display unit only has to be vertically moved in accordance with the back-and-forth movement of the reflecting means.
As a third aspect of the present invention, based on the second aspect, the display unit moving means has a display inclining means to incline a display surface of the luminous display unit in such a manner that an optical axis of the luminous display unit is unchanged when the luminous display unit is vertically moved.
According to the above vehicle-use head-up display system, the image to be looked at does not change when the eye points moves in the eye range.
As a fourth aspect of the present invention, based on the second aspect, the display unit moving means has a driving device to drive the luminous display unit and a guiding means, of an arcuate groove, to vertically guide the luminous display unit driven by the driving device and to incline a display surface of the luminous display unit in such a manner that an optical axis of the luminous display unit is unchanged when the luminous display unit is vertically moved.
According to the vehicle-use head-up display system, the image to be looked at does not change when the eye points moves in the eye range.
As a fifth aspect of the present invention, based on the second aspect, the display unit moving means has a driving device to drive the luminous display unit and a guiding means to vertically linearly guide the luminous display unit driven by the driving device.
According to the vehicle-use head-up display system, the display position can be adjusted without changing the depression angle.
As a sixth aspect of the present invention, based on the first aspect, the display-image moving means is a means to vertically move the display-image on the display surface of the luminous display unit.
According to the vehicle-use head-up display system, the luminous display unit does not need to be mechanically moved.
The above and other objects and features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.